Beat the recession! Highly cost effective DIY speaker build using the Audax AP170Z0

[TLS Guy]

I was actually looking at your site while you were adding. I was looking at it and when I moved pages more popped up. Thank you for doing all that work and adding all of that!
That is a little more than I was hoping to spend, but oi recognize there is a lot of value in the complete set. I think I will go ahead with it. I am just trying to decide if I will do it all at once or in a couple of groups.

I understood that you were saying that vertical is better, but didn't understand the comment about these driveres needing to be used horizontally. That is one of those things that I may need you to explain to me before I actually start building.

I looked at the Kappa build and thought it was a little more than I needed. But it will probably fit in well with this set and round out my system nicely. But it may have to wait a bit.

Now I see the post I made that was a little confusing. What I should have said is that MTM centers have to be placed horizontal for practical and aesthetic reasons, as a rule. However if you can place them vertically that would be better.

I think for what you will get the price is very reasonable. There are seven speakers here. You will build the crossovers from quality, but reasonably priced parts. The crossover is the heart of every speaker. On the vast majority of speakers below the 2K per pair range, the crossovers are built from very poor quality parts. For instance inductors usually have very narrow gauge wire, and iron cored inductors are used in the signal path often. Electrolytic capacitors often show up to save money. These have no place in speaker crossovers in my view. All these caps are good quality polypropylene.

I would build the three front speakers first, then the surrounds later. If you are using this for HT you need three good matched fronts off the bat.

Brace the cabinets well, like this.

Rout the driver cutouts, so that the drivers are flush with the front baffle. I would ise 1.5" thickness for the front baffle.

Now my models show the internal box volumes, Vb. However you have to add back the volumes displaced by driver, braces and the crossovers. This final volume usually ends up being Vb + 15% for the larger enclosures, and Vb + 20% for the smaller ones. The final number is called Vt.

Now make sure you get the port lengths right. As they come you will have to cut them down to Lv. specified for the box you are building. The parts are best glued together with Oatey plumbing cement.

When you build the crossovers space the inductors as far apart as you can, and where possible have their axes at right angles. This avoids mutual induction. Firmly anchor the inductors with plastic tie downs, and the larger capacitors also. If you don't you will have rattle.

This gives you the idea

If there are any other questions just ask. The idea is to have a set of good functioning speakers.

Happy building!

 

[TLS Guy]

We have two threads going on this speaker line at the moment. I would like to make this thread the one for further posts. That way it will save me time.

You might want to review some of the post on the other thread in case there are any points I missed in this thread.

 

[mc_chofo]

Dr. great you posted, that pictures of the xovers, lol you saved me one more question.

In the other hand, i was going to use 3/4 inch of mdf(if thats how it's called) which is .70inch, can i use .62inch insted of the 3/4? it's a little bit easier for me to get it, but if it's better 3/4 mdf i will use that one.

 

[TLS Guy]

Dr. great you posted, that pictures of the xovers, lol you saved me one more question.

In the other hand, i was going to use 3/4 inch of mdf(if thats how it's called) which is .70inch, can i use .62inch insted of the 3/4? it's a little bit easier for me to get it, but if it's better 3/4 mdf i will use that one.

I would not build those enclosures from anything thinner than 3/4 inch 0.7". I would use two thicknesses for the front panel.

Glad I beat you to your questions. When do you think you will have your components and be able to start your build?

Thanks for moving threads by the way!

 

[mc_chofo]

Thanks to you, for taking the time to help ups on designing and building this speakers. u have helped us a lot, thank you

well the MFD i think i will get it, tomorrow and i will start working on the cabinets on friday and i will finish them by monday-tuesday.

the xover parts and speakers, were shipped earlier today by madisound and parts-express, madisound sent me the package by Fedex and parts-express sent me by UPS, those were my only options, both have great service, but i had had problems, with both, Fedex and Ups 'cause they never find my shipping addrees, on this shipment i had chenged my shipping address to my billing address, so i hope there's no delate, i whink i will get those package by the end of the next week, or maybe a little more. i think i will get the speakers finished within 2 weeks.

 

[JLMEMT]

I think I have main points aleast. I ordered the 10 Audax drivers today, I should have them in a day or two as they are close to me. I will see if I can't work up a parts list for the rest and get them ordered tonight.

Now I understand the vertical comment better, thank you for the clarification. I am still tryng to figure it out, but may be able to make it vertical. I will probably have to build a shelf for it anyway.

It will take me a while to get these done I am sure. But I will probably try to figure things out and get the MDF soon so that I can get started.

 

[mc_chofo]

I have another doubt, well at the box properties you wrote, at the description su wrote that V=(total)2.123cu.ft, and now my doubt is, is that the outter volume, i'm asking this just to check if my design is correc, and if i'm correct, i have another question should the cabinet with be improved a lot, or the speaker response if i use 1" MDF insted the 3/4 i was planning to use? and if i do that and i'm right with the design, i should only ad that difference in messure of the wood to each side of the cabinet right?

 

[TLS Guy]

I have another doubt, well at the box properties you wrote, at the description su wrote that V=(total)2.123cu.ft, and now my doubt is, is that the outter volume, i'm asking this just to check if my design is correc, and if i'm correct, i have another question should the cabinet with be improved a lot, or the speaker response if i use 1" MDF insted the 3/4 i was planning to use? and if i do that and i'm right with the design, i should only ad that difference in messure of the wood to each side of the cabinet right?

This issue raises a lot of confusion. The speaker modeling will come up with an enclosure volume Vb. This is tuned by the port to Fb. Now the volume and port are worked out on Vb. Now the speakers, bracing and crossovers displace volume. So that Vb is lower than calculated by volume dimensions.

Now you need to make a good faith estimate of the volume of air displaced by the contents of the enclosure. This volume is added to Vb to come up with Vt. Now it is Vt you need to design the box to, and assume you have got the internal volume of air in the enclosure as close to Vb as possible.

There is a rough rule of thumb that works out quite well to come up with Vt. For small enclosures, Vb + 20% of Vb. For bigger enclosures, Vb + 10 to 15% of Vb.

When we are talking about Vb and Vt we are working with the internal dimensions. Always work with internal dimensions, and the the outer dimensions will be what ever they are depending on the thickness if your construction material.

Now as to the question of using 1". Within reason the thicker the better. So yes, 1" is better than 0.7" The choice is yours, and there in lies one of the big advantages of DIY.

 

[JLMEMT]

That post answered many of the things that I thought I had figured out, but wasn't sure of. Thank you.

I think the main question for me that remains, on the actual construction, is that you mentioned for the 2 1/2 ways the cabinent should be as narrow as possible. Does that hold true for the MTMs as well? Or is there a different build I should strive for on those?

 

[TLS Guy]

That post answered many of the things that I thought I had figured out, but wasn't sure of. Thank you.

I think the main question for me that remains, on the actual construction, is that you mentioned for the 2 1/2 ways the cabinent should be as narrow as possible. Does that hold true for the MTMs as well? Or is there a different build I should strive for on those?

I would still aim to build the cabinet narrow. Now you want the tweeter at seated ear level, about 36" from the floor. Since it is MTM, there will be a bass mid above the the tweeter. So the MTM will have to be a little taller, and less deep than the 2.5 way.

For the center MTM, I would use the 1 cu.ft enclosure. The tweeter should be in the center of the front panel, with the bass/mids either side.

I hope that clears things up.

 

[JLMEMT]

I worked up the plan for the main cabinets tonight. I don't have any fancy computerized pictures yet, but I will post what I came up with.

I have the interior cabinet 38" tall and 7" X 7" with bracing alternating every 6" or 7"" all the way down. I designed it around the top of the tweeter at 40". This gives me about 9" of space at the bottom that is not part of the sound chamber. I was thinking that I should put some ballast in these as they have a fairly narrow foot print and will be slightly top heavy and sitting on carpet.

Please let me know what you think.

Jason

 

[JLMEMT]

I worked up the plan for the main cabinets tonight. I don't have any fancy computerized pictures yet, but I will post what I came up with.

I have the interior cabinet 38" tall and 7" X 7" with bracing alternating every 6" or 7"" all the way down. I designed it around the top of the tweeter at 40". This gives me about 9" of space at the bottom that is not part of the sound chamber. I was thinking that I should put some ballast in these as they have a fairly narrow foot print and will be slightly top heavy and sitting on carpet.

Please let me know what you think.

Jason

That wasn't quite clear.

The total tower will be about 48" tall to give me the height I want at the tweeter, the sound chamber is about 38" so that leaves me the 9" of dead space below the bottom of the chamber. I thought that a finished box of about 9" X 9" and 48" tall with more weight at the top wouldn't be the best choice without ballast.

 

[shootermcgaven2]

what is a MTM design . and what is a 2.5 way?

 

[JLMEMT]

what is a MTM design . and what is a 2.5 way?

MTM is midrange, tweeter, midrange in that order.

Someone that understands it a bit better will have to explain the 2 1/2 way. A full 3 way would be a tweeter, midrange, and woofer. I believe the 2 1/2 way uses two of the same midrange drivers but the electronics, or the cabinet make it close to a 3 way, but because the two speakers are the same it can't be a true 3 way.

 

[TLS Guy]

That wasn't quite clear.

The total tower will be about 48" tall to give me the height I want at the tweeter, the sound chamber is about 38" so that leaves me the 9" of dead space below the bottom of the chamber. I thought that a finished box of about 9" X 9" and 48" tall with more weight at the top wouldn't be the best choice without ballast.

Sorry to ignore you today. we had a Minnesota blizzard yesterday, about 5.5 inches of snow with a really good wind behind it. I was on my 1848 Model a John Deere, clearing our 1/2 mile road in, my lot and a couple of neighbors.

That cabinet seems a little tall to me. I think it would look better if it were a few inches shorter. You should be able to shorten it 6 inches I would have thought.

It will be fine to put sand in the base though. Make sure it is clean and dry. If it is contaminated with organic material and or wet you will have a big problem.

 

[TLS Guy]

what is a MTM design . and what is a 2.5 way?

An MTM is mid tweeter mid. Odd order crossover slopes are generally used, so that the top driver and tweeter have a radiation pattern with a 15 degree downward tilt, and the tweeter lower driver a 15 degree up ward tilt. Horizontal dispersion is excellent, vertical dispersion is limited, which helps minimize floor and ceiling reflections.

I two and a half way speaker, uses another identical identical base mid as a fill driver.

Narrow cabinets have what is called diffraction loss. There is a roughly 6db per octave loss of response, which usually starts around 600 Hz for most speakers using small bass mids.

So take a look at the crossover, and frequency response graphs.

If you look at the red and blue lines, you will see they intersect at 3 kHz at the 6db down point.

Now if you look at the green line you will see the lower diver is fed via a network that rolls the power driver off starting about 175 Hz. Normally a first order network can be used for this, however this drivers have a rising response above 1 kHz to filter with changing orders is required to get the desired response. You will see that this fill driver raises the composite response (black line) starting about 600 Hz, and increases the output in the 100 to 175 Hz range by the required 6 db to compensate for the diffraction loss of the narrow cabinet.

This is the reason why 2.5 way designs are so popular and common.

 

[JLMEMT]

Sorry to ignore you today. we had a Minnesota blizzard yesterday, about 5.5 inches of snow with a really good wind behind it. I was on my 1848 Model a John Deere, clearing our 1/2 mile road in, my lot and a couple of neighbors.

That cabinet seems a little tall to me. I think it would look better if it were a few inches shorter. You should be able to shorten it 6 inches I would have thought.

It will be fine to put sand in the base though. Make sure it is clean and dry. If it is contaminated with organic material and or wet you will have a big problem.

No problem on that at all. I don't envy you a bit!!


This height is essentialy as short as I can make it putting the tweeter at 36". With her sitting on the couch her ear is right about 36", mine is closer to 39".

Do you think it would be better to loose about 5" - 6" of the dead space on the bottom and shorten it up?


I have a simple CAD drawing made up, but I am can't get it to show up well here. When I copied it to make it a jpeg it highlights everything and adds in all the adjustment points and make unreadable.

 

[TLS Guy]

No problem on that at all. I don't envy you a bit!!


This height is essentialy as short as I can make it putting the tweeter at 36". With her sitting on the couch her ear is right about 36", mine is closer to 39".

Do you think it would be better to loose about 5" - 6" of the dead space on the bottom and shorten it up?


I have a simple CAD drawing made up, but I am can't get it to show up well here. When I copied it to make it a jpeg it highlights everything and adds in all the adjustment points and make unreadable.

You should envy me! Yes, you ought to be downright jealous!

To spend a day in the woods on a clear crisp 0 degree day, sitting over two popping pistons, making music you can hear for miles around, is a great way to spend a day.

 

[JLMEMT]

I do understand what you are saying. ;-) But I don't like to be that cold! I had a pretty good time clearing things up about a month ago, at 35 degrees. I wouldn't mind snow at all, at about 60 degrees.

I haven't heard a two cylinder Deere for several years now, you just made me miss it a little. My grandfather had several. He had an old B that my uncle repainted for him about 10 years ago. He really liked that tractor. It was one he had used for many years on the farm. The last few years he just played with it mostly. Took him back I suppose.




Anyway, on the mains, Do you think I ought to shorten the cabinet some? It has been said that the optimum height is tweeter at ear level. Is there a range that you won't notice the difference? Am I being too literal?

 

[TLS Guy]

I do understand what you are saying. ;-) But I don't like to be that cold! I had a pretty good time clearing things up about a month ago, at 35 degrees. I wouldn't mind snow at all, at about 60 degrees.

I haven't heard a two cylinder Deere for several years now, you just made me miss it a little. My grandfather had several. He had an old B that my uncle repainted for him about 10 years ago. He really liked that tractor. It was one he had used for many years on the farm. The last few years he just played with it mostly. Took him back I suppose.




Anyway, on the mains, Do you think I ought to shorten the cabinet some? It has been said that the optimum height is tweeter at ear level. Is there a range that you won't notice the difference? Am I being too literal?

I nearly missed your last paragraph.

I think if you limit cabinet height to 42 to 44" it will make no difference acoustically, but will look much better. A narrow cabinet 48" tall does not look very good.

I find my 48 JD Model A dies a really good job of work. You should see the snow banks it has pushed up around here this winter. It starts first piston up. It is up an firing in well under a second from pressing the starter pedal. Show me a modern engine that will do that!